Numerical simulation of environmental and seismic loading of 10 MW monopile offshore wind turbines in liquefiable seabed

With the gradual application of 10 MW offshore wind turbines (OWTs) in the world, it is very important to study the liquefaction response of high power OWTs under multiple fields. In this paper, based on the state-dependent generalized plasticity model, a cross-scale refined analysis model of structure-monopile-liquefied seabed is established, and a method for the analysis of seismic dynamic response of large-diameter monopile offshore wind turbine (MOWT) in liquefiable seabed is developed. The applicability of the proposed method is validated through simulations of existing centrifuge model tests. Using this approach, the dynamic response characteristics of a 10 MW MOWT under combined wind, wave, and seismic loading are systematically investigated. The study reveals the spatial distribution of seabed liquefaction under varying earthquake intensities, elucidates the flow mechanisms, and explores the effects of different loading conditions and relative depth (Rd) of liquefiable sandy soil on the system’s response. The results show that: 1. Seismic loads significantly influence seabed liquefaction, while environmental loads primarily cause cumulative rotation in MOWT. 2. As Rd increases, the rate of pore pressure accumulation slows, and liquefaction depth, soil strain around the pile, MOWT deflection, and rotation angle all increase. 3. Liquefaction results in overall subsidence of the soil within a range of one pile diameter (1D, D = 10.375 m) around the pile, while soil flow and heave within a range of 2D behind the pile are the main contributors to foundation rotational failure.